Gun control expected to dominate US election

If there's a silver lining to come from the massacre in Orlando for gun control advocates, it's the timing -- five months before the US decides on its next President.

On one side there's Hillary Clinton, who wants assault weapons of the kind used by the gunman banned; and on the other, Donald Trump, who has the backing of the powerful NRA and says massacres wouldn't happen if the intended victims could fire back.

Omar Mateen, a US-born man with Afghan parents, killed 49 people at a gay nightclub in Orlando, Florida, at the weekend. His motivation has been disputed, with some reports saying he pledged allegiance to Islamic State, and others noting his hatred of gay people.

Whatever his reasons, his horrific act has one thing in common with many other mass shootings in recent years -- he used a military-grade assault rifle, specifically an AR-15. It's the same kind used in the San Bernadino shooting last year which left 12 dead, and the Sandy Hook Elementary School massacre of 2012, which saw 26 people killed -- including 20 six- and seven-year-olds.

"Hopefully now with yet another mass shooting -- this one the worst in our country's history -- this issue will finally be resolved," says Eric Ruben, a US gun law expert with the Brennan Centre for Justice in New York.

The AR-15 is also used by the US military in a modified form -- known as the M-16, made famous in movies like Apocalypse Now, Rambo: First Blood and Commando.

An AR-15 rifle (Reuters)

Barack Obama noted in a speech earlier this month that as President he is able to put people on a no-fly list to stop them getting on planes, but can't stop them buying an assault rifle "because of the National Rifle Association".

While the NRA is still "very strong", Mr Ruben says since Sandy Hook the anti-gun violence movement has grown.

"There are new organisations, there's a lot more support for common-sense gun laws," he says.

"Unlike past election cycles such as the 2008 and 2012 elections where Obama did not make gun violence prevention a major part of his campaign… you're seeing Hillary Clinton and others make gun violence prevention a major part of their campaigns."

He says there's "no doubt" with this attack the election will see more people voting on the issue gun control. But while banning assault weapons might make mass shootings harder, it's unlikely to make a dent in the overall number of US citizens killed in gun violence every year -- about 33,000 -- because most are caused by handguns.

But he believes even the Supreme Court would back a ban on assault weapons, if the incoming President -- presumably Ms Clinton -- made a move to ban them.

"The Supreme Court in a 2008 opinion said the handgun was the quintessential self-defence firearm. Nobody's saying that about assault weapons."